Organisers of Greece's top division have called off games scheduled for this weekend after referees announced a two-week walkout to protest the beating of a colleague by unknown assailants.

The country's football federation said on Thursday that Greek Cup matches would go ahead as scheduled. It said top-league referees called the walkout "for psychological reasons" after the "cowardly and unacceptable" assault.

Referee Thanassis Tzilos was attacked on Wednesday by three masked men near his home in Larissa. He was treated at a local hospital for head and leg injuries and released on Thursday.

Nobody has been arrested for the attack, which sports minister Giorgos Vassiliadis strongly condemned.

No top-flight games are scheduled from Dec. 24 to Jan. 11, the league's winter break. Organisers said games will resume after the protest ends Jan. 4.